From what I've found, there were something like 150 contingency orders to help hide the Palpatine's Order 66 and what it was meant to do.
The first time I saw Revenge of the Sith, I thought he gave the order "666", and I thought, cute, the devil, but then I learned it was actually "66". Does it mean anything?
Is it still referencing the devil? Is it just a number pulled from a hat? In short, what is the significance of the number in Palpatine's infamous line:
Execute Order 66
Update: George Lucas also did "American Graffiti" which references Route 66, but I don't how to connect that with killing Jedi. Jedi road kill?